The present invention relates to chip carriers, and more particularly the present invention relates to a chip carrier which has terminal calibrating ribs to keep the terminals at the same elevation for accurate and positive fastening to a printed circuit board.
An electronic chip is a precision integrated circuit comprised of resistors, diodes, etc., which may be damaged easily when directly welded to a printed circuit board. Therefore a chip carrier is commonly used to fasten a chip to a printed circuit board. There are two different types of chip carriers which are classified according to their mounting methods, namely, the welding process and the surface mounting technology. The present invention pertains to the surface mounting technology type of chip carriers.
A chip carrier according to the prior art, as shown in FIG. 1, is generally comprised of a base, and terminals. The base is made of plastic by an injection molding process, in the shape of a flat square block, having a series of terminal slots along the four sides thereof, which receive the terminals, and a recessed portion in the middle, which receives the chip. A number of terminals are connected by a connecting strip for quick insertion into the terminal slots on the base at the same side. Each terminal is comprised of a mounting contact and a connecting leg. The mounting contact is inserted in either terminal slot while the respective connecting leg projects out of the respective terminal slot for connecting to the printed circuit board. When inserted, the connecting strip is cut off. After the chip has been mounted on the base, the contacts of the chip are respectively disposed in contact with the mounting contacts of the terminals, and the connecting legs of the terminals are respectively connected to the circuit of the printed circuit board by employing a surface mounting technology. Because the connecting legs of the terminals are suspended out of the terminal slots respectively, they are not in perfect alignment (see FIG. 2) and should be corrected to be maintained at the same elevation so that the tin solder can be evenly distributed over the connecting legs while fastening the terminals to the printed circuit board. However, calibrating the horizontal alignment of the connecting legs is not easy, and requires special techniques and tools. While using a tool to correct the connecting legs of the terminals, the connecting legs may be easily damaged or broken.